The present invention relates to mechanical engineering, particularly, to designing engines, and more particularly, to a method for operating supersonic power plants for aircraft.
A method of operating a supersonic jet power plant, including dynamically compressing air in an inlet, feeding the pressurized air into a combustor, promoting turbulence in and adding heat to the air, and expanding combustion products in a jet nozzle is known in the prior art. See Inozemtsev N.V., Aircraft Gas Turbine Engines, Moscow, State Publishing House of Defense Industry, 1949, page 50.
The problems with the prior art method of operating a ramjet engine include its low efficiency at subsonic flight speeds, insufficient dynamics of the flight speed modulation and considerable hydraulic-pressure losses caused by great extension of the engine.
Another conventional method of operating a supersonic jet power plant comprising a turbojet, includes dynamically compressing air in an inlet, boosting the total air by a compressor which is rotationally driven by the engine, feeding the pressurized air into a combustion chamber and adding heat to the air, and expanding combustion products in the driving engine and a jet nozzle (Inozemtsev N.V. Aircraft Gas Turbine Engines, Moscow, State Publishing House of Defense Industry, 194, page 55).
Disadvantages of the prior art method include low efficiency of the power plant at Mach numbers under 1 and above 3 and insufficient dynamics when it is required to change drastically the flight speed.
Also known is a method of operating a supersonic hybrid jet power plant comprising a ducted turbojet and a ramjet, including dynamically compressing air in an inlet, boosting the air by a fan which is rotationally driven by an engine, feeding the pressurized air into a combustor, providing turbulence in and adding heat to the air, and expanding combustion products in a jet nozzle, wherein a portion of the pressurized air is fed to an intake manifold of the driving engine (Kurziner R.I. Jet Engines for High Supersonic Flight Speeds, Moscow, Mashinostroyenie, 1977, page 141).
The above referenced most pertinent prior art suffers low efficiency of the power plant at subsonic flight speeds, caused by inferior turbogenerator efficiency, and low dynamics of a vehicle both at subsonic and supersonic flight speeds.
It is an object of the present invention to improve efficiency of both a power plant and an aircraft, and to provide superior vehicle dynamics, thereby enhancing the aircraft reliability and flight safety.
The above object is attained in a method of operating a supersonic hybrid jet power plant, including dynamically compressing air in an inlet, boosting the air by a fan which is rotationally driven by an engine equipped with an intake manifold, feeding the pressurized air into a combustor, promoting turbulence in and supplying heat to the air, and expanding combustion products in a jet nozzle, a portion of the pressurized air being fed to the intake manifold of the driving engine, wherein the driving engine is a reciprocating two-stroke engine, a power supplied to the fan being reduced at supersonic flight regime, while maintaining the fan pressure ratio close to one.
To achieve the object of the invention, the heat addition to the pressurized air in the combustor is cut-off at subsonic flight regime.
The turbulence may be promoted in the pressurized air by the fan, turbulence conditions being varied by adjusting the rotation speed of the fan.
Alternatively, the turbulence may be promoted in the pressurized air by straightener blades of the fan, turbulence conditions being varied by adjusting an incidence angle of the straightener blades.
The power supplied to the fan may be reduced by throttling the intake manifold of the engine.
The drawing presents a schematic diagram of a power plant for implementing the method in accordance with the invention.